Power converter and integrated dc choke therefor

ABSTRACT

A power conversion system and a DC link choke therefore are presented, in which a continuous core structure is provided with first and second legs around which four or more windings are located, with one or more shunt structures providing a magnetic flux path between intermediate portions of the first and second legs.

REFERENCE TO RELATED APPLICATION

This application is a continuation of, and claims priority to and thebenefit of, U.S. patent application Ser. No. 13/177,100, filed on Jul.6, 2011, entitled POWER CONVERTER AND INTEGRATED DC CHOKE THEREFOR, theentirety of which application is hereby incorporated by reference.

BACKGROUND

Motor drives and other power conversion systems convert electrical powerfrom one form to another, and may be employed in a variety ofapplications such as powering an electric motor using power convertedfrom a single or multiphase AC input source. One common form of motordrive is a current source converter (CSC), in which a rectifier convertsinput AC power from a single or multiphase AC input source to provide DCcurrent to a DC link circuit. An output inverter converts the DC linkcurrent into single or multiphase AC output power to drive a motor load.Such power conversion systems may be subject to both differential andcommon mode voltages and currents, which can cause a variety of problemsincluding degradation of the power conversion system and/or the motorload. For instance, motors are susceptible to damage or performancedegradation caused by appearance of excessive common mode voltages onthe motor leads. Previously, low and medium voltage converters ofteninclude differential mode inductors as well as common mode controlapparatus to address these problems. However, separate differential andcommon mode devices are costly and occupy space in a power conversionsystem. Other techniques include modification of switching waveforms inone or both of the rectifier and inverter stages, but such techniquesoften require complicated switching control systems. Common mode anddifferential mode noise effects can also be addressed by using isolationtransformers within the power conversion system, but these transformersadd cost to the system and occupy space. Thus, there remains a need forimproved common mode and differential mode suppression apparatus andtechniques in power conversion systems.

U.S. Pat. No. 7,164,254 to Kerkman et al., issued Jan. 16, 2007 andassigned to the assignee of the present application discloses commonmode voltage reduction techniques in which the switching sequence ismodified to avoid using the zero vectors in order to reduce common modevoltages in the motor. The entirety of this patent is herebyincorporated by reference as if fully set forth herein.

U.S. Pat. No. 7,106,025 to Yin et al., issued Sep. 12, 2006 and assignedto the assignee of the present application discloses techniques forcanceling dead time effects in the algorithm to reduce common modevoltages produced by a three-phase power conversion device in arectifier/inverter variable frequency drive (VFD), the entirety of whichis hereby incorporated by reference as if fully set forth herein.

U.S. Pat. No. 5,422,619 to Yamaguchi et al., issued Jun. 6, 1995discloses a common mode choke coil with a couple of U-shaped cores and 4coils wound around legs of the cores, the entirety of which is herebyincorporated by reference as if fully set forth herein.

U.S. Pat. No. 5,905,642 to Hammond, issued May 18, 1999 discloses acommon mode reactor between a DC converter and an AC converter to reducecommon mode voltage from current source drives, the entirety of which ishereby incorporated by reference as if fully set forth herein.

U.S. Pat. No. 6,617,814 to Wu et al., issued Sep. 9, 2003 and assignedto the assignee of the present application discloses an integrated DClink choke and method for suppressing common-mode voltage and a motordrive, the entirety of which is hereby incorporated by reference as iffully set forth herein.

U.S. Pat. No. 6,819,070 to Kerkman et al., issued Nov. 16, 2004 andassigned to the assignee of the present application discloses inverterswitching control techniques to control reflected voltages in AC motordrives, the entirety of which is hereby incorporated by reference as iffully set forth herein.

U.S. Pat. No. 7,034,501 to Thunes et al., issued Apr. 25, 2007 andassigned to the assignee of the present application discloses gate pulsetime interval adjustment techniques for mitigating reflected waves in ACmotor drives, the entirety of which is hereby incorporated by referenceas if fully set forth herein.

SUMMARY

Various aspects of the present disclosure are now summarized tofacilitate a basic understanding of the disclosure, wherein this summaryis not an extensive overview of the disclosure, and is intended neitherto identify certain elements of the disclosure, nor to delineate thescope thereof. Rather, the primary purpose of this summary is to presentsome concepts of the disclosure in a simplified form prior to the moredetailed description that is presented hereinafter. The presentdisclosure presents power conversion systems and DC chokes with a corestructure including first and second legs having at least four windingsand one or more shunts providing a magnetic flux path betweenintermediate portions of the first and second core legs.

A power conversion system is provided which includes a rectifier, aninverter and a DC link choke providing coils coupled between therectifier and the inverter. The rectifier includes first and second DCoutput nodes, and the inverter has first and second DC input nodes. Thelink choke includes a core structure with first and second legs, both ofwhich include two ends and an intermediate portion. A third leg extendsbetween the first ends of the first and second legs, and a fourth legextends between the second ends of the first and second legs. In certainembodiments, the core structure includes a plurality of laminates. Incertain embodiments, moreover, the core structure has no gaps in orbetween the legs.

One or more shunts are provided between the intermediate portions of thefirst and second legs to provide a magnetic flux path between theintermediate portions, where a plurality of gaps are formed between theshunt(s) and the intermediate portions, wherein at least one of the gapsmay be zero in certain embodiments. Four or more windings are provided,with a first winding forming a first coil of the DC choke and havingfirst and second terminals, with the first winding forming at least oneturn around the first leg between the intermediate portion and the firstend of the first leg. A second winding forms at least one turn betweenthe intermediate portion and the second end of the first leg. Inaddition, a third winding forms at least one turn between theintermediate portion and the first end of the second leg, and a fourthwinding forms at least one turn between the intermediate portion and thesecond end of the second leg.

In certain embodiments, two or more shunts are provided in the magneticflux path between the intermediate portions of the first and secondlegs, where the shunts extend between the intermediate portions and format least one additional gaps between the at least two shunts.

In certain embodiments, the first and third windings are coupled inseries between the first DC output node of the rectifier and the firstDC input node of the inverter, and the second and fourth windings arecoupled in series with one another between the second rectifier DCoutput node and the second inverter DC input node.

In other embodiments, the first and second windings are coupled betweenthe first rectifier DC output node and the first inverter DC input node,with the third and fourth windings being coupled in series between thesecond rectifier DC output node and the second inverter DC input node.

In further embodiments, the first and fourth windings are coupledbetween the first rectifier DC output node and the first inverter DCinput node, and the second and third windings are coupled between thesecond rectifier DC output node and the second inverter DC input node.

In accordance with further aspects of the disclosure, an integrated DClink choke is provided, which is comprised of a core structure with fourlegs including a first leg having two ends and an intermediate portiondisposed therebetween as well as a second leg with two ends and anintermediate portion. A third leg of the core structure extends betweenthe first ends of the first and second legs, and a fourth leg extendsbetween the second ends of the first and second legs. One or more shuntsare provided which extend between the intermediate portions of the firstand second legs to provide a magnetic flux path therebetween, and aplurality of gaps is formed between the intermediate portions of thefirst and second legs and the shunt(s). The choke further comprises fouror more windings, including a first winding with first and secondterminals and forming at least one turn around the first leg between theintermediate portion and the first end of the first leg. A secondwinding is provided which forms at least one turn between theintermediate portion and the second end of the first leg. A thirdwinding is provided which forms at least one turn between theintermediate portion and the first end of the second leg, and a fourthwinding forms at least one turn between the intermediate portion and thesecond end of the second leg. In certain embodiments, more than one gapis provided between the intermediate portions of the first and secondlegs, and at least one additional gap is formed between the shunts. Incertain embodiments, moreover, the core structure includes a pluralityof laminates. In addition, the core structure in certain embodiments isa continuous structure having no gaps in or between the legs. In certainembodiments, the first and third windings are coupled in series with oneanother, and the second and fourth windings are coupled in series withone another. In other embodiments, the first and second windings arecoupled in series with one another, and the third and fourth windingsare coupled in series with one another. In still other embodiments, thefirst and fourth windings are coupled in series with one another, andthe second and third windings are coupled in series with one another.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and drawings set forth certain illustrativeimplementations of the disclosure in detail, which are indicative ofseveral exemplary ways in which the various principles of the disclosuremay be carried out. The illustrated examples, however, are notexhaustive of the many possible embodiments of the disclosure. Otherobjects, advantages and novel features of the disclosure will be setforth in the following detailed description when considered inconjunction with the drawings, in which:

FIG. 1 is a schematic diagram illustrating an exemplary current sourceconverter type variable frequency motor drive power conversion systemwith an integrated DC link choke according to one or more aspects of thepresent disclosure;

FIG. 2 is a front elevation view illustrating an exemplary corestructure for the integrated DC link choke, including a single shuntdisposed between intermediate portions of first and second vertical corelegs;

FIG. 3 is a front elevation view illustrating another exemplary DC linkchoke core structure having two shunts disposed between the verticalcore legs;

FIG. 4 is a front perspective view illustrating a laminated DC linkchoke core structure with a single shunt extending between the verticalcore legs;

FIG. 5 is a simplified front elevation view illustrating an exemplary DClink choke with first, second, third, and fourth windings located on thevertical core legs;

FIG. 6 is a schematic diagram illustrating an exemplary power conversionsystem with an integrated DC link choke in which the first and thirdwindings are connected in an upper DC link current path and the secondand fourth windings are connected in a lower DC link path;

FIG. 7 is a front elevation view illustrating connection of the DC linkchoke in the system of FIG. 6, as well as a differential mode equivalentcircuit and corresponding magnetic flux paths in the link choke corestructure;

FIG. 8 is a front elevation view illustrating the DC link choke in thesystem of FIG. 6 along with a common mode equivalent circuit andcorresponding magnetic flux paths in the link choke core structure;

FIG. 9 is a schematic diagram illustrating another motor drive powerconversion system embodiment including an integrated DC link choke withthe first and second windings connected in the upper DC link currentpath as well as the third and fourth windings connected in the lower DClink path;

FIG. 10 is a front elevation view illustrating connection of the DC linkchoke in the system of FIG. 9 and a differential mode equivalent circuitand corresponding magnetic flux paths in the link choke core structure;

FIG. 11 is a front elevation view illustrating connection of the DC linkchoke in the system of FIG. 9, as well as a common mode equivalentcircuit and corresponding magnetic flux paths in the link choke corestructure;

FIG. 12 is a schematic diagram illustrating another power conversionsystem embodiment with the first and fourth DC link choke windingsconnected in the upper DC link current path and the second and thirdwindings connected in the lower DC link path;

FIG. 13 is a front elevation view illustrating connection of the DC linkchoke in the system of FIG. 12, as well as a differential modeequivalent circuit and corresponding magnetic flux paths in the chokecore structure; and

FIG. 14 is a front elevation view illustrating the DC link choke in thesystem of FIG. 12, with a common mode equivalent circuit andcorresponding magnetic flux paths in the link choke core structure.

DETAILED DESCRIPTION

Referring now to the figures, several embodiments or implementations arehereinafter described in conjunction with the drawings, wherein likereference numerals are used to refer to like elements throughout, andwherein the various features are not necessarily drawn to scale.

The inventors have appreciated that existing common mode choke designssuffer from various issues and problems. Inherent weaknesses of thesedevices include the difficulty in avoiding the influence of localsaturation on common mode inductance. Moreover, windings in theseconventional devices with large numbers of turns can increase theproximity losses significantly. In this regard, common mode chokes havethus far been difficult to design due to complexities in calculating orsimulating flux distribution.

The disclosed embodiments provide a single link choke integratingdifferential mode inductors and common mode voltage suppression. Theseembodiments find utility in association with any form of powerconversion system, such as low-voltage and medium voltage motor drivetype power converters, and can be advantageously employed intransformerless configurations. Use of a single integrated link choke inan intermediate DC circuit reduces the total component count for motordrives and other power conversion systems compared with conventionalsolutions based on separate differential and common mode devices, andthe illustrated winding arrangements facilitate reduction in corematerial cost and size as well as copper loss, with the sharedcross-sectional area reducing the overall choke core weight. Thedisclosed approach can be used to provide a reliable cost-effectivesolution to common mode voltage problems in power converter systems,potentially without the need for active solutions and the associatedcomplex control requirements.

FIG. 1 illustrates an exemplary current source converter type variablefrequency motor drive power conversion system 2 that includes an inputrectifier 10 receiving single or multiphase AC input power from a powersource 4, as well as an inverter 20 providing single or multiphase ACoutput electrical power to drive a motor or other load 6. A link choke100 is provided which couples a DC output of the rectifier 10 with a DCinput of the inverter 20. In the illustrated embodiments, the DC linkchoke 100 couples the rectifier 10 and inverter 20 of a single powerconversion system 2. However, other embodiments are possible in whichadditional windings are added to a DC choke 100 to accommodate couplingbetween inverters 20 and rectifiers 10 of multiple power conversionsystems 2, with such windings providing coils to the respective powerconversion systems 24 controlling and/or otherwise addressingdifferential and common mode issues.

The rectifier 10 may be an active or passive rectifier circuit,including one or more passive diodes for rectifying AC input power toprovide DC output power. In other implementations, an active rectifiermay be used, including a plurality of switches (e.g., SGCTs, IGCTs,GTOs, thyristors, IGBTs with reverse blocking capability, etc.) operableaccording to corresponding control signals from a rectifier controlsystem (not shown) for selectively creating an intermediate DC linkcurrent flowing in first and second rectifier DC output terminals ornodes 11 and 12, respectively. The illustrated rectifier 10, moreover,is a three-phase active rectifier having six switching devices S1-S6individually coupled between one of the corresponding three input phaselines A, B, C and one of the DC output terminals 11, 12, where theswitching devices S1-S6 are individually operable according to acorresponding switching control input signal (not shown). In operation,the rectifier 10 provides a regulated DC link current to the choke 100via one or both of the nodes 11, 12, where the example of FIG. 1includes four coils L, with two coils L coupled in series with oneanother between the upper rectifier DC output terminal 11 and an theupper inverter DC input terminal 21, as well as another two coils Lcoupled in series with one another between a lower (e.g., second)rectifier DC output terminal 12 and a lower inverter DC input terminal22. In general, DC output current flows from the rectifier 10 throughthe first output terminal 11 into the link choke 100, and current isprovided from the link choke via the first inverter DC input terminal ornode 21 for conversion by the inverter 20 into single or multiphase ACelectrical output power to drive a motor 6 or other load. The lower DClink path provides a return current path for DC current flowing from theinverter 20 via the second DC input terminal or node 22 through the linkchoke 100 and returning to the rectifier 10 via the second rectifier DCoutput terminal or node 12. The system 2 may include suitable controls(not shown) for operating the rectifier switching devices S1-S6, and mayinclude feedback another regulation components (not shown) by which theDC link current can be measured to provide feedback for regulation ofthe DC current produced by the rectifier 10.

The inverter 20 in the illustrated example is a three-phase system whichreceives DC input current via the nodes 21 and 22, which are connectedto an array of inverter switching devices S7-S12 (e.g., SGCTs, IGCTs,GTOs, thyristors, IGBTs, etc.) which are selectively operated accordingto corresponding switching control input signals from an invertercontroller (not shown) to selectively couple individual ones of thethree-phase output lines U, V, W with one of the DC input nodes 21, 22according to any suitable switching control technique (e.g., such asspace vector modulation (SVM), selective harmonic elimination (SHE),etc.). By this operation, the DC link current received at the DC inputnode 21 by way of the link choke 100 from the rectifier 10 isselectively converted into multiphase AC output currents to drive themotor load 6. In other possible embodiments, a single-phase inverter 20may be used to drive a load 6. Moreover, the system 2 may be used todrive other forms of loads, and the disclosed concepts are not limitedto motor drives.

The DC link choke 100 forms an intermediate circuit that links theswitches S1-S6 of the rectifier 10 with the DC input nodes 21, 22 of theinverter 20. In certain embodiments, two coils L are provided in each ofthe upper and lower branches of the intermediate linking circuit, andsome embodiments are possible in which coils L of the choke 100 areprovided in only one of the upper and lower DC branches. Furtherimplementations are possible in which only a single coil L is providedin one of the linking circuit branches, with three or more coils L beingcoupled in the other branch. Moreover, while the illustrated embodimentsinclude four windings 110-140, more than four such windings can beprovided on a DC link choke 100 according to the present disclosure. Thepower conversion system 2 may include further components (not shown)such as input and/or output filter circuits including inductors and/orcapacitors, various feedback circuits to facilitate control of the DClink current and/or control of the output current provided to the motor6, various user interface components to facilitate operation of thesystem 2 generally or specific portions thereof, etc., the details ofwhich are omitted in order not to obscure the novel aspects of thepresent disclosure.

Referring also to FIGS. 2-5, the DC choke 100 is constructed using acore structure 150, which can be fabricated using any suitable inductoror transformer core material. As shown in FIG. 4, moreover, the corestructure 150 in certain embodiments is constructed using two or morelaminates 150L, which can be coated or uncoated and can be held togetheras a single core structure using any suitable techniques. FIG. 2illustrates an exemplary front view of the core structure 150, whichincludes first and second vertical legs 151 and 152, respectively, eachof which having an upper first end and a lower second end. The structure150 also includes a horizontally disposed third leg 153 extendingbetween the first (upper) ends of the first and second legs 151 and 152,as well as a horizontal fourth leg 154 extending between the second(lower) ends of the first and second legs 151 and 152. In certainembodiments, the illustrated structure 150 shown in FIG. 2 may bereplicated as two or more laminates 150L as shown in FIG. 4, or a singleunitary structure 150 may be provided. In addition, the exemplary corestructure 150 has no gaps in or between the legs 151-154, although otherembodiments are possible in which an air gap (or gap filled with othermaterial) is provided in or between some or all of the legs 151-154 orin which multiple air gaps are provided (not shown).

As seen in FIGS. 2 and 3, one or more shunts 160 are included in thelink choke 100 in order to provide a magnetic flux path betweenintermediate portions of the first and second legs 151 and 152. Theshunt or shunts 160 may be constructed of any suitable material such asthe same core material used to make the core structure 150. In theexample of FIG. 2, a single shunt 160 is disposed between theintermediate portions of the vertical core legs 151 and 152, where theshunt 160 is spaced from the legs 151 and 152, thereby defining firstand second gaps 155 and 156, respectively. In certain embodiments, thegaps 155 and 156 may be equal, or these gaps 155, 156 may be different.Moreover, in certain examples, one of the gaps 155, 156 may be zero,with the corresponding end of the shunt 160 contacting the correspondingleg 151, 152 of the core structure 150. In various embodiments, morethan one shunt 160 may be used. FIG. 3 illustrates one such example inwhich two shunts 160 are provided in the magnetic flux path between theintermediate portions of the vertical legs 151 and 152. As seen in FIG.3, the shunts 160 extend between, and are spaced from, the intermediateportions of the legs 151 and 152, and the shunts 160 are also spacedfrom one another to form an additional gap 157 therebetween.

FIG. 5 shows the integrated DC choke 100 (for the case in which a singleshunt 160 is used), including four exemplary windings 110, 120, 130 and140 provided on the first and second legs 151, 152, each of which formsa coil L coupled between the rectifier DC output and the inverter DCinput. The first winding 110 includes a first terminal 112 and a secondterminal 114 and forms one or more turns around the first leg 151between the intermediate portion thereof and the first (e.g., upper) endof the leg 151, where the beginning of the winding 110 starting from thefirst terminal 112 crosses in front of the upper portion of the firstleg 151 and the turns continue downward with the final portion of thewinding 110 crossing behind the leg 151 and ending at the secondterminal 114. In this manner, current flowing into the first terminal112 and out of the second terminal 114 will cause flux within the upperportion of the first leg 151 in the upward direction shown in FIG. 5.The second winding 120 has a first terminal 122 and a second terminal124 and forms at least one turn around the first leg 151 between theintermediate portion and the second (e.g., lower) end of the first leg151. As with the first winding 110, the beginning of the second winding120 starting from the terminal 122 passes in front of the first leg 151and the winding turns proceed downward to a final portion passing behindthe leg 151 and ending at the second terminal 124. Thus, current flowinginto the first terminal 122 and flowing out of the second terminal 124will create a flux in the upward direction in the lower part of thefirst leg 151.

The third and fourth windings 130 and 140 are wound around the secondcore leg 152 as seen in FIG. 5. In the embodiment of FIG. 5, the thirdwinding 130 has a first terminal 132 and a second terminal 134, and thiswinding 130 forms at least one turn around the second leg 152 betweenthe intermediate portion thereof and the first (upper) end of the secondleg 152. In this configuration, the beginning of the winding 130 beginsat the terminal 132 and passes behind the leg 152, extending downwardtherefrom toward the intermediate portion, with the final portion of thewinding 130 passing in front of the leg 152 and ending with the secondterminal 134. Thus, current flowing into the first terminal 132 and outof the second terminal 134 will create flux in the upward direction inthe upper portion of the second leg 152. The fourth winding 140 has afirst terminal 142 and a second terminal 144, with the beginning of thewinding 140 passing from the first terminal 142 behind the leg 152 andextending downward toward the second (lower) end of the leg 152 with thefinal portion of the winding 140 passing in front of the leg 152 andending at the second terminal 144. In this configuration, currentflowing into the first terminal 142 and out of the second terminal 144creates upward flux in the lower portion of the second leg 152 of thecore structure 150.

In certain embodiments, the number of turns in each of the windings 110,120, 130 and 140 are the same, and the first and second legs 151 and 152of the core structure 150 are generally of the same size, shape, andmaterial, whereby the inductances L associated with these windings120-140 are generally equal. In other embodiments, one or more of thesedesign parameters may be varied for individual ones of the windings 110,120, 130 and/or 140 whereby the coils L associated with the individualwindings 110-140 may be different. Moreover, as seen below, theinterconnection of the windings 110-140 within a given power conversionsystem to may be adjusted along with design parameters related to the DClink choke 100 itself in order to provide a variety of differentcombinations of inductance with respect to common mode voltages,differential mode currents, etc.

Referring now to FIGS. 6-8, FIG. 6 illustrates an exemplary embodimentof the power conversion system 2 with an integrated DC link choke 100 inwhich the first and third windings 110 and 130 are connected in theupper DC link current path of the converter 2, and the second and fourthwindings 120 and 140 are connected in the lower DC link path. Thisembodiment, like the others illustrated in the subsequent figures, mayinclude a single shunt 160 or may be provided with two or more shunts160 (e.g., as seen in FIG. 3 above). In the configuration of FIGS. 6-8,the windings 110 and 130 are coupled in series with one another betweenthe first DC output node 11 of the rectifier 10 and the first DC inputnode 21 of the inverter 20. In addition, the second and fourth windings120 and 140 are coupled in series with one another between the second DCoutput node 12 of the rectifier 10 and the second DC input node 22 ofthe inverter 20. FIGS. 7 and 8 show front views of the DC link choke 100in the system of FIG. 6, along with differential and common modeequivalent circuits, and the corresponding magnetic flux paths areillustrated in the link choke core structure 150. As seen in FIGS. 6-8,the first terminal 112 of the first winding 110 is coupled with thefirst rectifier DC output node 11, the second terminal 114 of the firstwinding 110 is coupled with the second terminal 134 of the third winding130, and the first terminal 132 of the third winding 130 is coupled withthe first inverter DC input node 21. In this manner, the windings 110and 130 and the coils L thereof are connected in series in the upper DClink branch between the rectifier 10 and the inverter 20. In addition,the first terminal 122 of the second winding 120 is coupled with thesecond DC output node 12 of the rectifier 10, the second terminal 124 ofthe winding 120 is coupled with the second winding 144 of the fourthwinding 140, and the first terminal of the winding 140 is coupled withthe second inverter DC input node 22. Thus, the second and fourthwindings 120 and 140 in the coils L thereof are coupled in series withone another in the lower DC link branch.

FIG. 7 illustrates operation of the DC choke 100 with respect todifferential current flow Idiff, and the figure includes an equivalentcircuit through which the differential current flows from the first DCoutput terminal 11 of the rectifier 10 into the first terminal 112 ofthe winding 110, then into the second terminal 134 of the third winding130, after which the differential current flows into the first terminal142 of the fourth winding 140 and then into the second terminal 124 ofthe second coil 120, finally flowing back through the second DC outputterminal 12 of the rectifier 10. For such differential current Idiff,flux paths 158 are created in the core structure 150 as shown in thebottom portion of FIG. 7, with magnetic flux flowing from right to leftthrough the magnetic flux path created between the intermediate portionsof the legs 151 and 152, the shunt 160, and the associated gaps (e.g.,gaps 155 and 156 as illustrated in FIGS. 2 and 4 above).

FIG. 8 illustrates this embodiment with respect to common mode currentIcom flowing in the converter 2, where the upper portion of the figureshows the equivalent circuit for this common mode situation. Asillustrated, the common mode circuit is the parallel combination of twoseries branches, with the first (upper) branch including the seriescombination of the first and third windings 110 and 130, and with thesecond (lower) branch including the series combination of the second andfourth windings 120 and 140. In this case, with the inductances beingequal, half the common mode current Icom flows in each of these circuitbranches, and the lower portion of FIG. 8 illustrates the resultingmagnetic flux flow within the core structure 150 (e.g., clockwise in thefigure flowing through the core legs 151, 153, 152, and 154sequentially). It is noted, that some magnetic flux may pass through theintermediate path that includes the shunt 160, although not a strictrequirement of the present disclosure. As seen in FIGS. 7 and 8, theintegrated DC link choke 100 may thus provide different levels ofeffective inductance with respect to differential mode current flowIdiff and common mode current Icom.

FIGS. 9-11 illustrate another embodiment of the current source convertermotor drive 2 in which the integrated DC link choke 100 has the firstand second windings 110 and 120 connected in the upper DC link currentpath, along with the third and fourth windings 130 and 140 connected inthe lower DC link path. In this embodiment, the first terminal 112 ofthe winding 110 is coupled with the first rectifier DC output node 11,the second terminal 114 of the winding 110 is coupled with the firstterminal 122 of the second winding 120, with the second terminal 124 ofthe winding 120 being coupled with the first inverter DC input node 21.In addition, the second terminal 134 of the third winding 130 is coupledwith the second rectifier DC output node 12, the first terminal 132 ofthe winding 130 is coupled with the second terminal 144 of the fourthwinding 140, and the first terminal 142 of the fourth winding 140 iscoupled with the second inverter DC input node 22.

As seen in FIG. 10, the equivalent circuit with respect to differentialcurrent Idiff begins with the first rectifier output terminal 11continuing into the first terminal 112 of the winding 110, and then intothe first terminal 122 of the second winding 120. The differentialcurrent Idiff continues through the inverter 22 to the first terminal142 of coil 140, and then into the first terminal 132 of the thirdwinding 130, returning to the rectifier 10 via the second outputterminal 12. This differential current flow in the DC link choke 100creates magnetic flux paths 158 as shown in the lower portion of FIG. 10(e.g., upward in both the vertical legs 151 and 152).

FIG. 11 illustrates the common mode situation, where the equivalentcircuit (upper portion of FIG. 11) includes the parallel combination of2 series circuit branches, where the first branch includes the windings110 and 120, and the second branch includes the windings 130 and 140,with half the common mode current Icom flowing through each of thesebranch circuits in some embodiments. This common mode current flow Icomcauses magnetic flux to flow in the path directions 158 indicated in thelower portion of FIG. 11. Thus, the variation in the interconnection ofthe windings 110-140 can be used (alone or in combination with otherchoke design parameters) to separately tailor the common mode and/ordifferential mode inductance provided by the choke 100.

FIGS. 12-14 illustrate yet another embodiment of the power conversionsystem 2, in which the first and fourth DC link choke windings 110 and140 are connected in series with one another in the upper DC linkcurrent path, and the second and third windings 120 and 130 areconnected in the lower DC link path. This cross-connection of thewindings 110-140 provides different flux path directions as seen inFIGS. 13 and 14. The first terminal 112 of the first winding 110 in thisembodiment is coupled with the first rectifier DC output node 11, andthe second terminal 114 of the winding 110 is coupled with the secondterminal 144 of the fourth winding 140. The first terminal 142 of thefourth winding 140, in turn, is coupled with the first inverter DC inputnode 21. The second DC output node 12 of the rectifier 10 is coupledwith the first terminal 120 of the second winding 120, the secondterminal 124 of the winding 120 is coupled with the second terminal 134of the third winding 130, and the first terminal 132 of the winding 130is coupled with the second inverter DC input node 22.

As seen in FIG. 13 for differential mode current Idiff, current flowingout of the first rectifier node 11 into the first terminal 112 of thewinding 110 proceeds into the second terminal 144 of winding 140, andproceeds from the first terminal 142 of the winding 140 through theinverter 20 into the first terminal 132 of the third winding 130, andthereafter into the second terminal 124 of the second winding 120,returning to the rectifier 10 via the second DC output node 12. Thiscauses magnetic flux 158 to flow upward in the upper portions of thecore legs 151 and 152 (resulting from the current flow through the coils110 and 130, respectively), and flux flows downward in the lowerportions of the legs 151 and 152 as a result of the current flow throughthe second and fourth coils 120 and 140.

The common mode operation is illustrated in FIG. 14, in which commonmode current Icom flows through the parallel combination of two branchcircuits, with the first branch circuit including the first and fourthcoils 110 and 140 and the second branch circuit including the coils 120and 130 as shown in the upper portion of the figure. As seen in thelower portion of FIG. 14, this results in upward magnetic flux flow inthe first core leg 151 and downward magnetic flux flow 158 in the secondcore leg 152.

The above examples are merely illustrative of several possibleembodiments of various aspects of the present disclosure, whereinequivalent alterations and/or modifications will occur to others skilledin the art upon reading and understanding this specification and theannexed drawings. In particular regard to the various functionsperformed by the above described components (assemblies, devices,systems, circuits, and the like), the terms (including a reference to a“means”) used to describe such components are intended to correspond,unless otherwise indicated, to any component, such as hardware,processor-executed software, or combinations thereof, which performs thespecified function of the described component (i.e., that isfunctionally equivalent), even though not structurally equivalent to thedisclosed structure which performs the function in the illustratedimplementations of the disclosure. In addition, although a particularfeature of the disclosure may have been disclosed with respect to onlyone of several implementations, such feature may be combined with one ormore other features of the other implementations as may be desired andadvantageous for any given or particular application. Also, to theextent that the terms “including”, “includes”, “having”, “has”, “with”,or variants thereof are used in the detailed description and/or in theclaims, such terms are intended to be inclusive in a manner similar tothe term “comprising”.

The following is claimed:
 1. A power conversion system, comprising: arectifier operative to provide DC output power at a rectifier DC output;an inverter comprising an inverter DC input, and operative to provide ACoutput power to a load; and a DC link choke comprising at least fourcoils coupled between the rectifier DC output and the inverter DC input,the DC link choke comprising: a core structure comprising: a first legincluding first and second ends and an intermediate portion disposedbetween the first and second ends, a second leg including first andsecond ends and an intermediate portion disposed between the first andsecond ends, a third leg extending between the first ends of the firstand second legs, and a fourth leg extending between the second ends ofthe first and second legs, at least one shunt providing a magnetic fluxpath between the intermediate portions of the first and second legs, afirst winding forming a first coil coupled between the rectifier DCoutput and the inverter DC input, the first winding forming at least oneturn around the first leg between the intermediate portion and the firstend of the first leg, a second winding forming a second coil coupledbetween the rectifier DC output and the inverter DC input, the secondwinding forming at least one turn around the first leg between theintermediate portion and the second end of the first leg, a thirdwinding forming a third coil coupled between the rectifier DC output andthe inverter DC input, the third winding forming at least one turnaround the second leg between the intermediate portion and the first endof the second leg, and a fourth winding forming a fourth coil coupledbetween the rectifier DC output and the inverter DC input, the fourthwinding forming at least one turn around the second leg between theintermediate portion and the second end of the second leg.
 2. The powerconversion system of claim 1, comprising at least two shunts providingthe magnetic flux path between intermediate portions of the first andsecond legs.
 3. The power conversion system of claim 1, wherein the corestructure comprises a plurality of laminates.
 4. The power conversionsystem of claim 1, wherein the core structure has no gaps in or betweenthe legs.
 5. The power conversion system of claim 1, wherein the firstwinding and the third winding are coupled in series with one anotherbetween a first DC output node of the rectifier and a first DC inputnode of the inverter, and wherein the second winding and the fourthwinding are coupled in series with one another between a second DCoutput node of the rectifier and a second DC input node of the inverter.6. The power conversion system of claim 5, wherein a first terminal ofthe first winding is coupled with the first DC output node of therectifier, a second terminal of the first winding is coupled with asecond terminal of the third winding, a first terminal of the thirdwinding is coupled with the first DC input node of the inverter, a firstterminal of the second winding is coupled with the second DC output nodeof the rectifier, a second terminal of the second winding is coupledwith a second terminal of the fourth winding, and a first terminal ofthe fourth winding is coupled with the second DC input node of theinverter.
 7. The power conversion system of claim 1, wherein the firstwinding and the second winding are coupled in series with one anotherbetween a first DC output node of the rectifier and a first DC inputnode of the inverter, and wherein the third winding and the fourthwinding are coupled in series with one another between a second DCoutput node of the rectifier and a second DC input node of the inverter.8. The power conversion system of claim 7, wherein a first terminal ofthe first winding is coupled with the first DC output node of therectifier, a second terminal of the first winding is coupled with afirst terminal of the second winding, a second terminal of the secondwinding is coupled with the first DC input node of the inverter, asecond terminal of the third winding is coupled with the second DCoutput node of the rectifier, a first terminal of the third winding iscoupled with a second terminal of the fourth winding, and a firstterminal of the fourth winding is coupled with the second DC input nodeof the inverter.
 9. The power conversion system of claim 1, wherein thefirst winding and the fourth winding are coupled in series with oneanother between a first DC output node of the rectifier and a first DCinput node of the inverter, and wherein the second winding and the thirdwinding are coupled in series with one another between a second DCoutput node of the rectifier and a second DC input node of the inverter.10. The power conversion system of claim 9, wherein a first terminal ofthe first winding is coupled with the first DC output node of therectifier, a second terminal of the first winding is coupled with asecond terminal of the fourth winding, a first terminal of the fourthwinding is coupled with the first DC input node of the inverter, a firstterminal of the second winding is coupled with the second DC output nodeof the rectifier, a second terminal of the second winding is coupledwith a second terminal of the third winding, and a first terminal of thethird winding is coupled with a second DC input node of the inverter.11. An integrated DC link choke, comprising: a core structurecomprising: a first leg including first and second ends and anintermediate portion disposed between the first and second ends, asecond leg including first and second ends and an intermediate portiondisposed between the first and second ends, a third leg extendingbetween the first ends of the first and second legs, and a fourth legextending between the second ends of the first and second legs; at leastone shunt providing a magnetic flux path between intermediate portionsof the first and second legs; a first winding forming a first coilcoupled between a rectifier DC output and an inverter DC input, thefirst winding forming at least one turn around the first leg between theintermediate portion and the first end of the first leg; a secondwinding forming a second coil coupled between the rectifier DC outputand the inverter DC input, the second winding forming at least one turnaround the first leg between the intermediate portion and the second endof the first leg; a third winding forming a third coil coupled betweenthe rectifier DC output and the inverter DC input, the third windingforming at least one turn around the second leg between the intermediateportion and the first end of the second leg; and a fourth windingforming a fourth coil coupled between the rectifier DC output and theinverter DC input, the fourth winding forming at least one turn aroundthe second leg between the intermediate portion and the second end ofthe second leg.
 12. The integrated DC link choke of claim 11, comprisingat least two shunts providing the magnetic flux path betweenintermediate portions of the first and second legs.
 13. The integratedDC link choke of claim 11, wherein the core structure comprises aplurality of laminates.
 14. The integrated DC link choke of claim 11,wherein the core structure has no gaps in or between the legs.
 15. Theintegrated DC link choke of claim 11, wherein the first winding and thethird winding are coupled in series with one another, and wherein thesecond winding and the fourth winding are coupled in series with oneanother.
 16. The integrated DC link choke of claim 15, wherein a secondterminal of the first winding is coupled with a second terminal of thethird winding, and wherein a second terminal of the second winding iscoupled with a second terminal of the fourth winding.
 17. The integratedDC link choke of claim 11, wherein the first winding and the secondwinding are coupled in series with one another, and wherein the thirdwinding in the fourth winding are coupled in series with one another.18. The integrated DC link choke of claim 17, wherein a second terminalof the first winding is coupled with a first terminal of the secondwinding, and wherein a first terminal of the third winding is coupledwith a second terminal of the fourth winding.
 19. The integrated DC linkchoke of claim 11, wherein the first winding and the fourth winding arecoupled in series with one another, and wherein the second winding andthe third winding are coupled in series with one another.
 20. Theintegrated DC link choke of claim 19, wherein a second terminal of thefirst winding is coupled with a second terminal of the fourth winding,and wherein a second terminal of the second winding is coupled with asecond terminal of the third winding.